[PATCH v4 10/18] KVM: arm64: Introduce __pkvm_host_share_guest()
Quentin Perret
qperret at google.com
Wed Dec 18 11:40:51 PST 2024
In preparation for handling guest stage-2 mappings at EL2, introduce a
new pKVM hypercall allowing to share pages with non-protected guests.
Tested-by: Fuad Tabba <tabba at google.com>
Reviewed-by: Fuad Tabba <tabba at google.com>
Signed-off-by: Quentin Perret <qperret at google.com>
---
arch/arm64/include/asm/kvm_asm.h | 1 +
arch/arm64/include/asm/kvm_host.h | 3 +
arch/arm64/kvm/hyp/include/nvhe/mem_protect.h | 2 +
arch/arm64/kvm/hyp/include/nvhe/memory.h | 4 +-
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 34 +++++++++
arch/arm64/kvm/hyp/nvhe/mem_protect.c | 72 +++++++++++++++++++
arch/arm64/kvm/hyp/nvhe/pkvm.c | 8 +++
7 files changed, 123 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 89c0fac69551..449337f5b2a3 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -65,6 +65,7 @@ enum __kvm_host_smccc_func {
/* Hypercalls available after pKVM finalisation */
__KVM_HOST_SMCCC_FUNC___pkvm_host_share_hyp,
__KVM_HOST_SMCCC_FUNC___pkvm_host_unshare_hyp,
+ __KVM_HOST_SMCCC_FUNC___pkvm_host_share_guest,
__KVM_HOST_SMCCC_FUNC___kvm_adjust_pc,
__KVM_HOST_SMCCC_FUNC___kvm_vcpu_run,
__KVM_HOST_SMCCC_FUNC___kvm_flush_vm_context,
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index e18e9244d17a..1246f1d01dbf 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -771,6 +771,9 @@ struct kvm_vcpu_arch {
/* Cache some mmu pages needed inside spinlock regions */
struct kvm_mmu_memory_cache mmu_page_cache;
+ /* Pages to top-up the pKVM/EL2 guest pool */
+ struct kvm_hyp_memcache pkvm_memcache;
+
/* Virtual SError ESR to restore when HCR_EL2.VSE is set */
u64 vsesr_el2;
diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
index 25038ac705d8..15b8956051b6 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
@@ -39,6 +39,8 @@ int __pkvm_host_donate_hyp(u64 pfn, u64 nr_pages);
int __pkvm_hyp_donate_host(u64 pfn, u64 nr_pages);
int __pkvm_host_share_ffa(u64 pfn, u64 nr_pages);
int __pkvm_host_unshare_ffa(u64 pfn, u64 nr_pages);
+int __pkvm_host_share_guest(u64 pfn, u64 gfn, struct pkvm_hyp_vcpu *vcpu,
+ enum kvm_pgtable_prot prot);
bool addr_is_memory(phys_addr_t phys);
int host_stage2_idmap_locked(phys_addr_t addr, u64 size, enum kvm_pgtable_prot prot);
diff --git a/arch/arm64/kvm/hyp/include/nvhe/memory.h b/arch/arm64/kvm/hyp/include/nvhe/memory.h
index 2a5eabf4b753..34233d586060 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/memory.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/memory.h
@@ -46,6 +46,8 @@ struct hyp_page {
/* Host (non-meta) state. Guarded by the host stage-2 lock. */
enum pkvm_page_state host_state : 8;
+
+ u32 host_share_guest_count;
};
extern u64 __hyp_vmemmap;
@@ -68,7 +70,7 @@ static inline phys_addr_t hyp_virt_to_phys(void *addr)
static inline struct hyp_page *hyp_phys_to_page(phys_addr_t phys)
{
- BUILD_BUG_ON(sizeof(struct hyp_page) != sizeof(u32));
+ BUILD_BUG_ON(sizeof(struct hyp_page) != sizeof(u64));
return &hyp_vmemmap[hyp_phys_to_pfn(phys)];
}
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 95d78db315b3..d659462fbf5d 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -211,6 +211,39 @@ static void handle___kvm_vcpu_run(struct kvm_cpu_context *host_ctxt)
cpu_reg(host_ctxt, 1) = ret;
}
+static int pkvm_refill_memcache(struct pkvm_hyp_vcpu *hyp_vcpu)
+{
+ struct kvm_vcpu *host_vcpu = hyp_vcpu->host_vcpu;
+
+ return refill_memcache(&hyp_vcpu->vcpu.arch.pkvm_memcache,
+ host_vcpu->arch.pkvm_memcache.nr_pages,
+ &host_vcpu->arch.pkvm_memcache);
+}
+
+static void handle___pkvm_host_share_guest(struct kvm_cpu_context *host_ctxt)
+{
+ DECLARE_REG(u64, pfn, host_ctxt, 1);
+ DECLARE_REG(u64, gfn, host_ctxt, 2);
+ DECLARE_REG(enum kvm_pgtable_prot, prot, host_ctxt, 3);
+ struct pkvm_hyp_vcpu *hyp_vcpu;
+ int ret = -EINVAL;
+
+ if (!is_protected_kvm_enabled())
+ goto out;
+
+ hyp_vcpu = pkvm_get_loaded_hyp_vcpu();
+ if (!hyp_vcpu || pkvm_hyp_vcpu_is_protected(hyp_vcpu))
+ goto out;
+
+ ret = pkvm_refill_memcache(hyp_vcpu);
+ if (ret)
+ goto out;
+
+ ret = __pkvm_host_share_guest(pfn, gfn, hyp_vcpu, prot);
+out:
+ cpu_reg(host_ctxt, 1) = ret;
+}
+
static void handle___kvm_adjust_pc(struct kvm_cpu_context *host_ctxt)
{
DECLARE_REG(struct kvm_vcpu *, vcpu, host_ctxt, 1);
@@ -420,6 +453,7 @@ static const hcall_t host_hcall[] = {
HANDLE_FUNC(__pkvm_host_share_hyp),
HANDLE_FUNC(__pkvm_host_unshare_hyp),
+ HANDLE_FUNC(__pkvm_host_share_guest),
HANDLE_FUNC(__kvm_adjust_pc),
HANDLE_FUNC(__kvm_vcpu_run),
HANDLE_FUNC(__kvm_flush_vm_context),
diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index 12bb5445fe47..fb9592e721cf 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -867,6 +867,27 @@ static int hyp_complete_donation(u64 addr,
return pkvm_create_mappings_locked(start, end, prot);
}
+static enum pkvm_page_state guest_get_page_state(kvm_pte_t pte, u64 addr)
+{
+ if (!kvm_pte_valid(pte))
+ return PKVM_NOPAGE;
+
+ return pkvm_getstate(kvm_pgtable_stage2_pte_prot(pte));
+}
+
+static int __guest_check_page_state_range(struct pkvm_hyp_vcpu *vcpu, u64 addr,
+ u64 size, enum pkvm_page_state state)
+{
+ struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(vcpu);
+ struct check_walk_data d = {
+ .desired = state,
+ .get_page_state = guest_get_page_state,
+ };
+
+ hyp_assert_lock_held(&vm->lock);
+ return check_page_state_range(&vm->pgt, addr, size, &d);
+}
+
static int check_share(struct pkvm_mem_share *share)
{
const struct pkvm_mem_transition *tx = &share->tx;
@@ -1349,3 +1370,54 @@ int __pkvm_host_unshare_ffa(u64 pfn, u64 nr_pages)
return ret;
}
+
+int __pkvm_host_share_guest(u64 pfn, u64 gfn, struct pkvm_hyp_vcpu *vcpu,
+ enum kvm_pgtable_prot prot)
+{
+ struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(vcpu);
+ u64 phys = hyp_pfn_to_phys(pfn);
+ u64 ipa = hyp_pfn_to_phys(gfn);
+ struct hyp_page *page;
+ int ret;
+
+ if (prot & ~KVM_PGTABLE_PROT_RWX)
+ return -EINVAL;
+
+ ret = check_range_allowed_memory(phys, phys + PAGE_SIZE);
+ if (ret)
+ return ret;
+
+ host_lock_component();
+ guest_lock_component(vm);
+
+ ret = __guest_check_page_state_range(vcpu, ipa, PAGE_SIZE, PKVM_NOPAGE);
+ if (ret)
+ goto unlock;
+
+ page = hyp_phys_to_page(phys);
+ switch (page->host_state) {
+ case PKVM_PAGE_OWNED:
+ WARN_ON(__host_set_page_state_range(phys, PAGE_SIZE, PKVM_PAGE_SHARED_OWNED));
+ break;
+ case PKVM_PAGE_SHARED_OWNED:
+ if (page->host_share_guest_count)
+ break;
+ /* Only host to np-guest multi-sharing is tolerated */
+ WARN_ON(1);
+ fallthrough;
+ default:
+ ret = -EPERM;
+ goto unlock;
+ }
+
+ WARN_ON(kvm_pgtable_stage2_map(&vm->pgt, ipa, PAGE_SIZE, phys,
+ pkvm_mkstate(prot, PKVM_PAGE_SHARED_BORROWED),
+ &vcpu->vcpu.arch.pkvm_memcache, 0));
+ page->host_share_guest_count++;
+
+unlock:
+ guest_unlock_component(vm);
+ host_unlock_component();
+
+ return ret;
+}
diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c
index 496d186efb03..0109c36566c8 100644
--- a/arch/arm64/kvm/hyp/nvhe/pkvm.c
+++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c
@@ -795,6 +795,14 @@ int __pkvm_teardown_vm(pkvm_handle_t handle)
/* Push the metadata pages to the teardown memcache */
for (idx = 0; idx < hyp_vm->nr_vcpus; ++idx) {
struct pkvm_hyp_vcpu *hyp_vcpu = hyp_vm->vcpus[idx];
+ struct kvm_hyp_memcache *vcpu_mc = &hyp_vcpu->vcpu.arch.pkvm_memcache;
+
+ while (vcpu_mc->nr_pages) {
+ void *addr = pop_hyp_memcache(vcpu_mc, hyp_phys_to_virt);
+
+ push_hyp_memcache(mc, addr, hyp_virt_to_phys);
+ unmap_donated_memory_noclear(addr, PAGE_SIZE);
+ }
teardown_donated_memory(mc, hyp_vcpu, sizeof(*hyp_vcpu));
}
--
2.47.1.613.gc27f4b7a9f-goog
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